A transducer which converts electromagnetic radiation in the infrared, visible, and ultraviolet regions into electrical quantities such as voltage, current, or resistance. Also called photo cell.

An effect noted primarily in wet snow conditions when snow clings to the sides of a precipitation gauge and gradually accumulates until the gauge orifice is capped with accumulated snow. This effect can be minimized by using large collectors, and wind scr ...

Precipitation of very small, white opaque particles of ice, fairly flat or elongated, with diameters less than 1 mm. The solid equivalent of drizzle.

Apparatus from which the nature and time of precipitation may be determined.

Hygrometer in which the dew (frost) point is determined by observing the temperature of an artificially cooled surface at the moment at which dew (frost) first appears on it.

Contraction for pilot balloon observation.

See hurricane beacon.

Same as dropsonde.

Amount of solar radiation incident, per unit area and time, on a surface which is perpendicular to the radiation and is situated at the outer limit of the atmosphere, the earth being at its mean distance from the sun. It equals approximately 2.00 ly/ min ...

The closeness of agreement among measurements of the same value of the same quantity where the individual measurements are made under different defined conditions, i.e. by different methods or with different measuring instruments.

A type of climatic diagram whose coordinates are some form of temperature vs. a form of humidity or precipitation.

Temperature assumed by an unsaturated air parcel when brought adiabatically to a standard pressure (1,000 mb).

Name applied to a class of instruments which measure the liquid content of the atmosphere.

A unit of signaling speed representing the number of code elements sent per second; often, bits per second.

The range of operating conditions within which a device is designed to operate and for which operating influences are stated. See operating conditions, reference operating conditions.

Operation mode of a communication circuit in which each end can simultaneously transmit and receive.

The probability distribution of random errors, typically a normal distribution with a zero mean.

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

A clockwise change in wind direction. Veering winds with height are indicative of warm air advection (WAA).

Thermometer used for measuring the highest temperature attained during a given interval of time, for example, a day.